#include <bits/stdc++.h>
typedef long long ll;
#define FOR(i,x,y) for(ll i=x; i<y; i++)
#define FORNEG(i,x,y) for(ll i=x; i>y; i--)
using namespace std;
vector<ll> edges[200005];
ll realans = 0;
int dp(ll a, ll p){
ll ans = 0;
if (edges[a].size() <= 1) ans = 1;
for (auto&i : edges[a]){
if (i != p) ans += dp(i, a);
}
if (p!=-1) realans += 1 + (ans+1)%2;
return 1 + (ans+1)%2;
}
int main(){
ll n,q;
cin >> n >> q;
FOR(i,0,n-1){
ll a,b;
cin >> a >> b;
edges[a].push_back(b);
edges[b].push_back(a);
}
FOR(i,0,q){
ll d; cin >> d;
ll cur = n+1;
FOR(k,0,d){
ll temp; cin >> temp;
edges[temp].push_back(cur++);
}
ll root = -1;
ll cnt = d;
FOR(j,1,n+1){
if (edges[j].size() != 1){
root = j;
}else{
cnt++;
}
}
if (cnt%2==1) cout << -1 << "\n";
else{
realans = 0;
dp(root, -1);
cout << realans << "\n";
}
FOR(i,1,n+1){
while (edges[i].size() && edges[i][edges[i].size()-1]>n){
edges[i].pop_back();
}
}
}
}
